nflog_fd, nflog_callback_register, nflog_handle_packet, nflog_bind_group, nflog_unbind_group,

       Generated automatically by Doxygen for libnetfilter_log from the source code.

libnetfilter_log                                  Version 1.0.2                                           Log(3)

       Once libnetfilter_log library has been initialised (See LibrarySetup), it is possible to bind the program
       to a specific group. This can be done using nflog_bind_group().

       The group can then be tuned via nflog_set_mode() among many others.

       Here's a little code snippet that binds to the group 100:

               printf('binding this socket to group 100\0);
               gh = nflog_bind_group(h, 100);
               if (!gh) {
                       fprintf(stderr, 'no handle for group 100\0);
                       exit(1);
               }

               printf('setting copy_packet mode\0);
               if (nflog_set_mode(gh, NFULNL_COPY_PACKET, 0xffff) < 0) {
                       fprintf(stderr, 'can't set packet copy mode\0);
                       exit(1);
               }

       Next step is the handling of incoming packets which can be done via a loop:

               fd = nflog_fd(h);

               while ((rv = recv(fd, buf, sizeof(buf), 0)) && rv >= 0) {
                       printf('pkt received (len=%u)\0, rv);
                       nflog_handle_packet(h, buf, rv);
               }

       Data and information about the packet can be fetched by using message parsing functions.

       Seealso:LibrarySetup man page (mannflog_open)
           Parsing man page (mannflog_get_gid)

structnflog_g_handle*nflog_bind_group(structnflog_handle*h,uint16_tnum)
       nflog_bind_group - bind a new handle to a specific group number.

       Parametersh Netfilter log handle obtained via call to nflog_open()num the number of the group to bind to

       Returns
           an nflog_g_handle for the newly created group or NULL on failure.

       ErrorsEBUSY This process has already binded to the group
           EOPNOTSUPP Request rejected by kernel. Another process has already binded to the group, or this
           process is not running as root

       Definition at line 464 of file libnetfilter_log.c.

   intnflog_callback_register(structnflog_g_handle*gh,nflog_callback*cb,void*data)
       nflog_callback_register - register function to process packets

       Parametersgh Netfilter log group handle obtained by call to nflog_bind_group()cb callback function to call for each logged packet
           data custom data to pass to the callback function

       Returns
           0

       Definition at line 343 of file libnetfilter_log.c.

   intnflog_fd(structnflog_handle*h)
       nflog_fd - get the file descriptor associated with the nflog handler

       Parametersh handler obtained via call to nflog_open()Returns
           a file descriptor for the netlink connection associated with the given log connection handle. The
           file descriptor can then be used for receiving the logged packets for processing.

       Definition at line 245 of file libnetfilter_log.c.

   intnflog_handle_packet(structnflog_handle*h,char*buf,intlen)
       nflog_handle_packet - handle a packet received from the nflog subsystem

       Parametersh Netfilter log handle obtained via call to nflog_open()buf nflog data received from the kernel
           len length of packet data in buffer

       Triggers an associated callback for each packet contained in buf. Data can be read from the queue using
       nflog_fd() and recv(). See example code in the Detailed Description.

       Returns
           0 on success, -1 if either the callback returned -ve or buf contains corrupt data. errno is not
           reliably set: caller should zeroise first if interested.

       Definition at line 366 of file libnetfilter_log.c.

   intnflog_set_flags(structnflog_g_handle*gh,uint16_tflags)
       nflog_set_flags - set the nflog flags for this group

       Parametersgh Netfilter log group handle obtained by call to nflog_bind_group().
           flags Flags that you want to set

       There are two existing flags:

        - NFULNL_CFG_F_SEQ: This enables local nflog sequence numbering.
        - NFULNL_CFG_F_SEQ_GLOBAL: This enables global nflog sequence numbering.
        - NFULNL_CFG_F_CONNTRACK: This enables to acquire related conntrack.

       Returns
           0 on success, -1 on failure with errno set.

       Errors
           from underlying calls, in exceptional circumstances

       Definition at line 664 of file libnetfilter_log.c.

   intnflog_set_mode(structnflog_g_handle*gh,uint8_tmode,uint32_trange)
       nflog_set_mode - set the amount of packet data that nflog copies to userspace

       Parametersgh Netfilter log group handle obtained by call to nflog_bind_group().
           mode the part of the packet that we are interested in
           range size of the packet that we want to get

       Sets the amount of data to be copied to userspace for each packet logged to the given group.

       • NFULNL_COPY_NONE - do not copy any data

       • NFULNL_COPY_META - copy only packet metadata

       • NFULNL_COPY_PACKET - copy entire packet

       Returns
           0 on success, -1 on failure with errno set.

       Errors
           from underlying calls, in exceptional circumstances

       Definition at line 534 of file libnetfilter_log.c.

   intnflog_set_nlbufsiz(structnflog_g_handle*gh,uint32_tnlbufsiz)
       nflog_set_nlbufsiz - set the size of the nflog buffer for this group

       Parametersgh Netfilter log group handle obtained by call to nflog_bind_group().
           nlbufsiz Size of the nflog buffer

       This function sets the size (in bytes) of the buffer that is used to stack log messages in nflog.

       Warning
           The  use of this function is strongly discouraged. The default buffer size (which is one memory page)
           provides the optimum results in terms of performance. Do not use this function in your applications.

       Returns
           0 on success, -1 on failure with errno set.

       Errors
           from underlying calls, in exceptional circumstances

       Definition at line 627 of file libnetfilter_log.c.

   intnflog_set_qthresh(structnflog_g_handle*gh,uint32_tqthresh)
       nflog_set_qthresh - set the maximum amount of logs in buffer for this group

       Parametersgh Netfilter log group handle obtained by call to nflog_bind_group().
           qthresh Maximum number of log entries

       This function determines the maximum number of log entries in the buffer until it is pushed to userspace.

       Returns
           0 on success, -1 on failure with errno set.

       Errors
           from underlying calls, in exceptional circumstances

       Definition at line 596 of file libnetfilter_log.c.

   intnflog_set_timeout(structnflog_g_handle*gh,uint32_ttimeout)
       nflog_set_timeout - set the maximum time to push log buffer for this group

       Parametersgh Netfilter log group handle obtained by call to nflog_bind_group().
           timeout Time to wait until the log buffer is pushed to userspace

       This function allows one to set the maximum time that nflog waits until  it  pushes  the  log  buffer  to
       userspace  if  no  new  logged  packets  have occured. Basically, nflog implements a buffer to reduce the
       computational cost of delivering the log message to userspace.

       Returns
           0 on success, -1 on failure with errno set.

       Errors
           from underlying calls, in exceptional circumstances

       Definition at line 569 of file libnetfilter_log.c.

   intnflog_unbind_group(structnflog_g_handle*gh)
       nflog_unbind_group - unbind a group handle.

       Parametersgh Netfilter log group handle obtained via nflog_bind_group()Returns
           0 on success, -1 on failure with errno set.

       Errors
           from underlying calls, in exceptional circumstances

       Definition at line 506 of file libnetfilter_log.c.

       nflog_fd, nflog_callback_register, nflog_handle_packet, nflog_bind_group, nflog_unbind_group,
       nflog_set_mode, nflog_set_timeout, nflog_set_qthresh, nflog_set_nlbufsiz, nflog_set_flags - Group
       handling

#include<stddef.h>#include<libnetfilter_log/libnetfilter_log.h>

       int nflog_fd (struct nflog_handle *h)
       int nflog_callback_register (struct nflog_g_handle *gh, nflog_callback *cb, void *data)
       int nflog_handle_packet (struct nflog_handle *h, char *buf, int len)
       struct nflog_g_handle * nflog_bind_group (struct nflog_handle *h, uint16_t num)
       int nflog_unbind_group (struct nflog_g_handle *gh)
       int nflog_set_mode (struct nflog_g_handle *gh, uint8_t mode, uint32_t range)
       int nflog_set_timeout (struct nflog_g_handle *gh, uint32_t timeout)
       int nflog_set_qthresh (struct nflog_g_handle *gh, uint32_t qthresh)
       int nflog_set_nlbufsiz (struct nflog_g_handle *gh, uint32_t nlbufsiz)
       int nflog_set_flags (struct nflog_g_handle *gh, uint16_t flags)